Anti-glare film, manufacturing method for same, polarizing plate and image display device

ABSTRACT

The present invention provides an anti-glare film having an excellent anti-glare property, and sufficiently suppressing white muddiness and scintillation, generation of cracks in a process for attaching the films to polarizing elements and a fabrication process of liquid crystal cells, and changes of an anti-glare property over time, even if the film is used in a high definition display. 
     An anti-glare film comprises a light-transmitting substrate; and a diffusion layer having a surface roughness and provided on at least one surface of the light-transmitting substrate, in which the diffusion layer is obtainable by applying, on the at least one surface of the light-transmitting substrate, a coating composition including organic fine particles (A) and a radiation curable binder that includes a (meth)acrylate monomer as an essential component, drying the coating composition to form a coating, and curing the coating, the organic fine particles (A) in the diffusion layer each have an impregnation layer that is impregnated with the radiation curable binder, and the impregnation layer has an average thickness of 0.01 to 1.0 μm.

TECHNICAL FIELD

The present invention relates to an anti-glare film, a method forproducing the anti-glare film, a polarizer, and an image display device.

BACKGROUND ART

Image display devices such as cathode ray tubes (CRTs), liquid crystaldisplay devices (LCDs), plasma display devices (PDPs),electroluminescence display devices (ELDs), and electronic paper aregenerally provided with optical laminated bodies for antireflection onthe outermost surface thereof. Such optical laminated bodies forantireflection suppress reflection of images and decrease thereflectivity by light diffusion or interference of light.

As one of such antireflection optical laminated bodies, an anti-glarefilm including an anti-glare layer that has a surface roughness and isprovided on a surface of a transparent substrate is known. Such asurface roughness of an anti-glare film diffuses ambient light, wherebya decrease in visibility can be prevented.

Conventional anti-glare films are known in which anti-glare layersformed by applying resins containing filler such as silicon dioxide(silica) on surfaces of transparent base films (see, for example, PatentLiteratures 1 and 2).

For example, in such anti-glare films, a surface roughness is formed byadding cohesive particles, an inorganic filler and/or an organic fillerin a resin; laminating a film with unevenness on an anti-glare layer;and phase separation using compatibility among compounds such as two ormore different polymers, which constitute a binder.

In all such conventional anti-glare films, a light diffusion functionand an anti-glare function are obtained by the effect of a surface shapeof the anti-glare layer. In order to increase such an anti-glarefunction, the size of the surface roughness needs to be increased.However, the large-sized projection and depression increases a haze of acoating, whereby white muddiness is generated.

Further, the twinkling brightness which is called scintillation isgenerated on the surfaces of conventional anti-glare films, whichresults in a decrease in visibility of display screens.

In recent years, high definition liquid crystal displays have beendeveloped. However, scintillation is generated in such high definitionliquid crystal displays when conventional anti-glare films are usedtherein. Such scintillation is a serious problem.

Furthermore, in the conventional anti-glare films, cracks are generatedduring a process for adhering the films to polarizing elements or afabrication process of liquid crystal cells, at, for example, aninterface between light-transmitting fine particles and alight-transmitting resin that are included in an anti-glare layer.Furthermore, in the conventional anti-glare films, anti-glareperformance and a scintillation state are changed over time due to thehaze variation in response to temperature and moisture changes.Therefore, the conventional anti-glare films are less resistant tomoisture and heat.

Patent Literature 3 discloses an anti-glare material obtainable bymixing a binder resin with resin beads in which 70% or more thereof isswollen with a solvent.

In an anti-glare film provided with an anti-glare layer including suchresin beads that are previously swollen with a solvent, the adhesion atthe interface between the resin beads and the binder resin is expectedto be improved. Such an anti-glare film is expected to be used in highdefinition displays.

In such an anti-glare film provided with an anti-glare layer includingresin beads that are previously swollen with a solvent, the adhesion atthe interface between the swollen resin beads and the binder resin inthe anti-glare layer is improved only by an anchor effect created at theinterface. Therefore, the adhesion and the like can be further improved.

Patent Literature 4 discloses a method for producing a light diffusionfilm in which the density of light-transmitting fine particles, acoating composition, and the average particle size of light-transmittingfine particles are in a specific relation to one another. PatentLiterature 5 discloses an optical film including light-transmittingparticles having a certain average particle size that depends on thethickness of a light diffusion layer. Patent Literature 6 discloses anoptical film including an anti-glare layer formed from a coatingcomposition in which a binder and two types of resin fine particlesdifferent in particle sizes and swelling rates that satisfy a certainrelation with each other are dispersed in a dispersion. PatentLiterature 7 discloses a method for producing a light diffusion film,including a coating composition for a light diffusion layer. The coatingcomposition includes light-transmitting fine particles, alight-transmitting resin containing a certain amount of alight-transmitting polymer with a molecular weight of 1000 or more, anda solvent.

However, Patent Literatures 4 to 7 do not disclose at all thatlight-transmitting fine particles are impregnated with a binder, and donot disclose at all, either the effect exerted by the impregnation oflight-transmitting fine particles with a binder. Therefore, theanti-glare films disclosed in the patent literatures do not sufficientlyachieve an anti-glare property, prevention of white muddiness, andprevention of scintillation.

Therefore, in conventional anti-glare films, generation of cracks at theinterface between resin beads and a binder resin is required to beprevented at a high level in a process for attaching the films topolarizing elements and a fabrication process of liquid crystal cells.Furthermore, white muddiness is required to be reduced by reducingreflection at the interface between a binder and resin beads andscintillation is also required to be prevented by appropriatelydispersing resin beads.

CITATION LIST Patent Literature

-   Patent Literature 1: JP-A Hei-6-18706-   Patent Literature 2: JP-A Hei-10-20103-   Patent Literature 3: JP-A 2005-281476-   Patent Literature 4: JP-A 2006-113561-   Patent Literature 5: JP-A 2007-249191-   Patent Literature 6: JP-A 2009-271255-   Patent Literature 7: JP-A 2006-154791

SUMMARY OF INVENTION Technical Problem

The present invention has been made in view of the above-described stateof the art. The present invention aims to provide an anti-glare filmhaving an excellent anti-glare property, sufficiently suppressing whitemuddiness and scintillation, even if the film is used in a highdefinition display, and further suppressing changes of an anti-glareproperty and the like over time and generation of cracks in a processfor attaching the films to polarizing elements and a fabrication processof liquid crystal cells. The present invention further aims to provide amethod for producing the anti-glare film, a polarizing plate and animage display device using the anti-glare film.

Solution to Problem

The present invention is an anti-glare film, comprising: alight-transmitting substrate; and a diffusion layer having a surfaceroughness and provided on at least one surface of the light-transmittingsubstrate, wherein the diffusion layer is obtainable by applying, on theat least one surface of the light-transmitting substrate, a coatingcomposition including organic fine particles (A) and a radiation curablebinder that includes a (meth)acrylate monomer as an essential component,diving the coating composition to form a coating, and curing thecoating, the organic fine particles (A) in the diffusion layer each havean impregnation layer that is impregnated with the radiation curablebinder, and the impregnation layer has an average thickness of 0.01 to1.0 μm.

In the anti-glare film of the present invention, a haze variation duringa 60° C., 90% RH, 1000-hour moisture and heat resistance test ispreferably 1.5% or less.

The diffusion layer preferably further includes fine particles (B) withan average particle size of smaller than the average particle size ofthe organic fine particles (A).

The coating composition used for the anti-glare film of the presentinvention preferably includes at least a solvent that swells the organicfine particles (A).

Further, Δ_(A) and Δ_(B) preferably satisfy the formula (1):

|Δ_(A)|<|Δ_(B)|  (1)

wherein ΔA represents a difference between a refractive index of theradiation curable binder and a refractive index of the organic fineparticles (A) and Δ_(B) represents a difference between a refractiveindex of the radiation curable binder and a refractive index of the fineparticles (B).

Further, D_(A)1 and D_(A)2 preferably satisfy the formula (2):

0.01 μm<D _(A)2−D _(A)1<1.0 μm  (2)

wherein D_(A)1 represents an average particle size of the organic fineparticles (A) and D_(A)2 represents an average particle size of theorganic fine particles (A) in the diffusion layer.

Further, D_(A)1, D_(B)1, D_(A)2, and D_(B)2 preferably satisfy theformula (3):

1.0 μm>D _(A)2−D _(A)1>D _(B)2−D _(B)1≧0  (3)

wherein D_(A)1 represents an average particle size of the organic fineparticles (A), D_(B)1 represents an average particle size of the fineparticles (B), D_(A)2 represents an average particle size of the organicfine particles (A) in the diffusion layer, and D_(B)2 represents anaverage particle size of the fine particles (B) in the diffusion layer.

In the anti-glare film of the present invention, the fine particles (B)are preferably organic fine particles.

The diffusion layer preferably further includes a lamellar inorganiccompound. The lamellar inorganic compound is preferably talc.

It is preferable that the diffusion layer has projections at positionscorresponding to the organic fine particles (A) in the surface of thediffusion layer, the projections having a height lower than the heightof projections at positions corresponding to organic fine particles (C)in the surface of a diffusion layer (C),

wherein the diffusion layer (C) satisfy all the following requirements(1), (2), and (3):

Requirement (1): the diffusion layer (C) is formed in the sameconditions as the diffusion layer containing the organic fine particles(A), except that the organic fine particles (C) are used instead of theorganic fine particles (A);

Requirement (2): the average particle size of the organic fine particles(C) in the diffusion layer (C) is the same as the average particle sizeof the organic fine particles (A) in the diffusion layer; and

Requirement (3): no impregnation layer is formed in each of the organicfine particles (C) in the diffusion layer (C).

The present invention is also a method for producing an anti-glare filmthat includes a light-transmitting substrate and a diffusion layerhaving a surface roughness and provided on least one surface of thelight-transmitting substrate, the method comprising forming thediffusion layer by applying, on the at least one surface of thelight-transmitting substrate, a coating composition including organicfine particles (A), a radiation curable binder that includes a(meth)acrylate monomer as an essential component, and a solvent; dryingthe coating composition to form a coating; and curing the coating, theradiation curable binder and/or the solvent including a component thatswells the organic fine particles (A), the organic fine particles (A)each having an impregnation layer that is impregnated with the radiationcurable binder and has an average thickness of 0.01 to 1.0 μm.

The present invention is also a polarizer provided with a polarizingelement. The polarizer comprises the anti-glare film of the presentinvention provided on a surface of the polarizing element.

The present invention is also an image display device comprising, theanti-glare film of the present invention or the polarizer of the presentinvention on the outermost surface of the image display device.

The present invention will be described in detail below.

The anti-glare film of the present invention includes alight-transmitting substrate and a diffusion layer having a surfaceroughness and provided on at least one surface of the light-transmittingsubstrate.

The light-transmitting substrate is preferably excellent in smoothness,heat resistance, and mechanical strength. Specific examples of materialsfor the light-transmitting substrate include polyester (polyethyleneterephthalate, polyethylene naphthalate), cellulose triacetate,cellulose diacetate, cellulose acetate butyrate, polyamides, polyimides,polyethersulfone, polysulfone, polypropylene, polymethylpentene,polyvinyl chloride, polyvinyl acetal, polyetherketones, polymethylmethacrylate, polycarbonate or polyurethane, and thermoplastic resinssuch as cyclopolyolefins. Particularly, polyester (polyethyleneterephthalate, polyethylene naphthalate) and cellulose triacetate arepreferred.

The light-transmitting substrate is preferably used in a film-like shapewhich is rich in flexibility. Further, a plate of the above-describedthermoplastic resins or a plate-like body such as a glass plate may beused as the Substrate in the case where curability is needed in the useof the substrate.

The thickness of the light-transmitting substrate is preferably 20 to300 μm, and more preferably is the upper limit of 200 μm and the lowerlimit of 30 μm. When the light-transmitting substrate is in a plate-likeshape, the thickness may be outside the aforementioned range.

When an anti-glare layer is formed on the light-transmitting substrate,in order to improve the adhesive property, the light-transmittingsubstrate may be previously subjected to physical treatment such ascorona discharge treatment, plasma treatment, saponification treatment,and oxidation treatment, or may be previously coated with an anchoragent or a paint composition called a primer.

In the anti-glare film of the present invention, the diffusion layer isobtainable by applying, on the at least one surface of thelight-transmitting substrate, a coating composition including organicfine particles (A) and a radiation curable binder that includes a(meth)acrylate monomer as an essential component, preferably furtherincluding fine particles (B), and more preferably further including asolvent that swells the organic fine particles (A); drying the coatingcomposition to form a coating; and curing the coating.

Unless otherwise noted, the diffusion layer includes the organic fineparticles (A) and the fine particles (B). Unless otherwise stated, thediffusion layer indicates a cured coating layer.

The organic fine particles (A) in the diffusion layer each have animpregnation layer that is impregnated with the radiation curablebinder. Hereinafter, organic particles (A) free from the impregnationlayer are referred to as “organic fine particles (A1)”, and organic fineparticles (A) with the impregnation layer, that is, organic fineparticles (A) in a diffusion layer are referred to as “organic fineparticles (A2)”.

The organic fine particles (A2) having such an impregnation layer arehighly adhered to a cured product (hereinafter, also referred to as abinder resin) of the radiation curable binder in the diffusion layer.The radiation curable binder and a material constituting the organicfine particles (A2) are mixed in the impregnation layer of the organicfine particles (A2). Therefore, the refractive index of the impregnationlayer is intermediate between those of the radiation curable binder andthe organic fine particles (A). Therefore, reflection of light passingthrough the diffusion layer can be preferably reduced at the interfacebetween the organic fine particles (A2) (impregnation layer) and thebinder resin. In addition, the impregnation layer has an appropriatethickness and the center portion of each of the organic fine particles(A2) retains the same refractive index as that of the original organicfine particles (A). Therefore, scintillation can be preferably preventedwithout reducing the internal diffusion.

In the conventional anti-glare films, anti-glare performance and ascintillation state may be changed over time due to the haze variationin response to temperature and moisture changes. However, the anti-glarefilm of the present invention employing such an impregnation layer isremarkably stable (has excellent moisture and heat resistance) withoutbeing affected by such problems. This is assumed to result from thefollowing mechanism.

The moisture and heat resistance test of the conventional anti-glarefilm containing organic fine particles shows that moisture entered intothe diffusion layer acts on the distortion of the interface between theorganic fine particles and the binder resin. As a result, an increase inthe distortion, generation of a micro crack, and the like are caused.Thereby, an anti-glare property is assumed to vary over time (hazevariation). The distortion is remarkably observed in organic fineparticles with a large particle size.

However, the distortion of the interface between the present organicfine particles (A2) with the impregnation layer and the binder resin isreduced. Therefore, the increase in the distortion, the generation of amicro crack, and the like are assumed to be suppressed. Further, asdescribed below, since in the presence of the radiation curable binderand the solvent, the impregnation layer is preferably obtainable byswelling the organic fine particles (A1) with the radiation curablebinder and/or the solvent, the organic fine, particles (A2) areextremely rich in flexibility. Therefore, projections formed atpositions corresponding to the organic fine particles (A2) in thesurface of the diffusion layer are gently curved. This is explained indetail below.

The material, constituting the organic fine particles (A1) is preferablya material that can be swollen with the following radiation curablebinder and/or the following solvent. Specific examples of the materialinclude a silicone resin, a polyester resin, a styrene resin, an acrylicresin, an olefin resin, and copolymers thereof. Among these, an acrylicresin is preferably used. Particularly, a cross-linked acrylic resin inwhich a cross-linking degree is changed, for example, by improvingcross-link density when the resin is formed into particles is morepreferably used. The term “resin” used herein includes resin componentssuch as a reactive or nonreactive polymer, a reactive or nonreactivemonomer, and a reactive or nonreactive oligomer.

Organic fine particles formed of an acrylic resin, a styrene resin, oran acrylic-styrene copolymer may be produced using an acrylic-styrenecopolymer resin as a material when produced by a generally known method.If the organic fine particles (A1) are core-shell fine particles,styrene fine particles using acrylic resin fine particles as a core andacrylic fine particles using styrene resin fine particles as a core.Therefore, in the present description, acrylic fine particles, styrenefine particles, and acrylic-styrene copolymer fine particles aredetermined by characteristics (for example, refractive index) of resinsforming the particles. For example, fine particles with a refractiveindex of less than 1.50 are acrylic fine particles, fine particles witha refractive index of 1.50 or more and less than 1.59 areacrylic-styrene copolymer fine particles, and fine particles with arefractive index of 1.59 or more are styrene fine particles.

As the cross-linked acrylic resin, for example, homopolymers andcopolymers obtainable by polymerization (e.g., suspensionpolymerization) of an acrylic monomer such as acrylic acid, acrylicester, methacrylic acid, methacrylic ester, acrylamide, andacrylonitrile using a polymerization initiator such as persulfuric acidand a crosslinking agent such as ethylene glycol dimethacrylate.

As the acrylic monomer, a cross-linked acrylic resin obtainable usingmethyl methacrylate is particularly preferred. The thickness of theimpregnation layer is controllable by adjusting the degree of swellingby the radiation curable binder and/or the solvent described below. Inorder to do this, the cross-linking degree is previously changed so thatthe amount of the radiation curable binder used for impregnation is inthe preferred range.

The average particle size of the organic fine particles (A1) ispreferably 0.5 to 15.0 μm, and more preferably 1.0 to 10.0 μm. If theaverage particle size is less than 0.5 μm, the anti-glare property andthe prevention of scintillation of the anti-glare film of the presentinvention may be insufficient. If the average particle size exceeds 15.0μm, an image of a display using the anti-glare film of the presentinvention is vaguely-outlined, lacks in precision, and is grainy.Thereby, the display quality may deteriorate.

The average particle size means the average particle size of fineparticles mono-dispersed in the diffusion layer (particles with auniform shape); or the size of particles existing the most in thediffusion layer in the case that the particles are irregular particleswith broad particle size distribution. The particles existing the mostare determined by particle size distribution measurement. If thediffusion layer includes only particles, the particle size thereof maybe determined by the Coulter counter method or the like. In addition tothe method, fine particles in a cured layer may be determined by SEMcross-sectional observation or microscopic observation using transmittedlight.

The organic fine particles (A2) in the diffusion layer each have animpregnation layer.

The impregnation layer is a layer impregnated with the radiation curablebinder. The radiation curable binder penetrates into the organic fineparticles (A2) in the diffusion layer from the outer surface toward thecenter. The impregnation layer is impregnated with a low molecularcomponent of the radiation curable binder, namely impregnated mainlywith a monomer. A polymerized radiation curable binder, which is apolymer component, in the form of a polymer or an oligomer, is hard topenetrate into the organic fine particles (A2).

The impregnation layer may be observed, for example, by cross sectionalmicroscope (e.g., SEM) observation of the organic fine particles (A2) inthe diffusion layer.

All components constituting the radiation curable binder may penetrateinto the impregnation layer or part of the components may penetrate intothe impregnation layer.

In the anti-glare film of the present invention, if the diffusion layerincludes the fine, particles (B) described below, the organic fineparticles (A2) preferably have an average particle size larger than thatof the fine particles (B) in the diffusion layer. If the averageparticle size of the organic fine particles (A2) is equal to or smallerthan that of the fine particles (B) in the diffusion layer, projectionsat positions corresponding to the organic fine particles (B) in thesurface of the diffusion layer may be distinctly formed, whereby whitemuddiness may not be sufficiently suppressed.

The impregnation layer has an average thickness of 0.01 to 1.0 μm. Ifthe thickness is less than 0.01 μm, the effect of the formation of theimpregnation layer cannot be sufficiently obtained. If the thicknessexceeds 1.0 μm, an internal diffusion function of the organic fineparticles (A2) is not sufficiently exerted, whereby the effect of theprevention of scintillation cannot be sufficiently obtained. The lowerlimit of the average thickness of the impregnation layer is preferably0.1 μm, and the upper limit of the average thickness of the impregnationlayer is preferably 0.8 μm. The impregnation layer with the thickness inthe above range further enhances the effect. The size of the centerportion free from the impregnation layer is preferably a wavelength oflight or more in view of securing the internal, diffusion function andthe prevention of scintillation.

The average thickness of the impregnation layer means the averagethickness of the impregnation layer of the organic fine particles (A)when the layer is viewed in cross section. The particles (A) areobserved in cross-sectional SEM images of the anti-glare film.Specifically, the average thickness of the impregnation layer can bedetermined by the following ways. The cross section of the diffusionlayer is observed at 3000× to 50000× magnification in five SEM images,in each of which at least one fine particle with an impregnation layerexists, and the images are taken; the thickness of the impregnationlayer is measured at two points for each fine particle; and the averageof the resulting 10 measurement values was adopted for the averagethickness of the impregnation layer. The two points selected for themeasurement of the thickness of the impregnation layer are such that theinterface between fine particles and a binder resin around the fineparticles is relatively clearly observed and the amount of the resinbinder penetrating into the impregnation layer is the largest.

The organic fine particles generally have a cross-linked structure. Thedegree of swelling by the radiation curable binder and/or the solventdepends on the cross-linking degree. Generally, the degree of swellingbecomes low with increase in the cross-linking degree, and the degree ofswelling becomes high with decrease in the cross-linking degree.Therefore, if the material constituting the organic fine particles (A2)is the above-described cross-linked acrylic resin, the thickness of theimpregnation layer may be controlled in a desired range by adjusting thecross-linking degree of the cross-linked acrylic resin. It is morepreferable that, in the organic fine particles (A2), the nearer thecenter portion, the higher the cross-linking degree, in view ofantireflection and prevention of scintillation. It is most preferablethat a portion under the impregnation layer of the organic fine particle(A2) has such a cross-linking degree that no impregnating ability isprovided, and the nearer the surface, the lower the cross-linkingdegree.

In the anti-glare film of the present invention, D_(A)1 and D_(A)2preferably satisfy the formula (2):

0.01 μm<D _(A)2−D _(A)1<1.0 μm  (2)

wherein D_(A)1 represents an average particle size of the organic fineparticles (A1) and D_(A)2 represents an average particle size of theorganic fine particles (A2) in the diffusion layer.

In the formula (2), if “D_(A)2−D_(A)1” is 0.01 μm or less, the thicknessof the impregnation layer is too small, whereby no effect of theformation of the impregnation layer may be obtained. If “D_(A)2−D_(A)1”is 1.0 μm or more, an internal diffusion function is not sufficientlyexerted, whereby an effect of the prevention of scintillation may not beenhanced.

The lower limit of “D_(A)2−D_(A)1” is more preferably 0.1 μm, and theupper limit of “D_(A)2−D_(A)1” is more preferably 0.5 μm. If“D_(A)2−D_(A)1” is within the above range, the effect described abovemay be achieved.

In the anti-glare film of the present invention, anti-glare films areprepared using coating compositions including organic fine particleswith different cross-linking degrees, and organic fine particlesachieving a suitable impregnation degree are selected from these as theorganic fine particles (A1).

The organic fine particles (A2) in the diffusion layer preferably do notaggregate in the thickness direction (longitudinal direction) of thediffusion layer. If the organic fine particles (A2) in the diffusionlayer aggregate to be piled up in the thickness direction of thediffusion layer, large projections may be formed in the surface of thediffusion layer at positions corresponding to the aggregation of theorganic fine particles (A2), whereby white muddiness and scintillationmay be caused in the anti-glare film of the present invention. Theaggregation of the organic fine particles (A2) in the diffusion layermay be suitably prevented, for example, by adding a lamellar inorganiccompound in the diffusion layer. The above problems are less likely tobe caused by the organic fine particles (A2) aggregated in theperpendicular direction (transverse direction) against the thicknessdirection of the diffusion layer, compared to the aggregation formedonly in the longitudinal direction. However, too large aggregationcauses similar problems. Therefore, the lamellar inorganic compound ispreferably added like in the case where the particles are aggregated inthe longitudinal direction.

The amount of the organic fine particles (A1) in the coating compositionis preferably, but is not particularly limited to, 0.5 to 30 parts bymass based on 100 parts by mass of the radiation curable binderdescribed below. If the amount is less than 0.5 parts by mass, asufficient surface roughness of the diffusion layer cannot be formed,which may results in an insufficient anti-glare property of theanti-glare film of the present invention. If the amount exceeds 30 partsby mass, the organic fine particles (A1) are likely to aggregate in thecoating composition, and are likely to aggregate in the longitudinaldirection or the transverse direction in the diffusion layer. Thereby,large projections are formed in the surface of the diffusion layer,which may cause white muddiness and scintillation. The lower limit ofthe amount of the organic fine particles (A1) is more preferably 1.0part by mass, and the upper limit of the amount is more preferably 20parts by mass. If the amount is within the above range, the effectsdescribed above may be certainly achieved.

The fine particles (B) are particles not swollen with the radiationcurable binder and the solvent in the coating composition.

Here, the “particles not swollen” includes particles slightly swollenwith the radiation curable binder and the solvent in addition toparticles not swollen with the binder and the solvent at all. The fineparticles (B) in the diffusion layer include an impregnation layer thatis similar to that of the organic fine particles (A2). The “particlesslightly swollen” are the fine particles (B) in which the averagethickness of the impregnation layer is smaller than that of theimpregnation layer of the organic fine particles (A) and is less than0.1 μm. The fine particles (B) preferably have a slight impregnationlayer in view of the suppression of a variation of anti-glareperformance over time.

The formation of the impregnation layer of the fine particles (B) in thediffusion layer is confirmed, for example, by observation of the crosssection of the particles under a microscope (e.g., SEM).

In the following description, the fine particles (B) before being addedto the coating composition are referred to as “fine particles (B1)” andthe fine particles (B) in the diffusion layer are referred to as “fineparticles (B2)”.

The fine particles (B1) are not particularly limited as long as theparticles are not, swollen with the radiation curable binder and thesolvent. Examples of these include inorganic particles such as silicafine particles; and organic particles, having a high cross-linkingdegree, of a silicone resin, a polystyrene resin, a melamine resin, apolyester resin, an acrylic resin, an olefin resin, and copolymers ofthese resin. Particularly, organic particles with an easy-controlledrefractive index or an easy-controlled particle size are preferred. Thefine particles (B1) may be used alone, or two or more types thereof maybe used in combination.

Particularly, polystyrene fine particles and/or acrylic-styrenecopolymer fine particles are preferably used because the refractiveindex thereof is high and the difference between such a high refractiveindex and the refractive index of the binder (a refractive index of theradiation curable binder is generally about 1.48 to about 1.54) islikely to increase and the internal diffusion of the particles areeasily achieved. The fine particles (B) are described as organicparticles below.

In the following description, the term “high cross-linked” or “lowcross-linked” is used for modifying the term fine particles. Thedefinitions of the terms “high cross-linked” and “low cross-linked” aredescribed below. 190 parts by mass of a mixture of toluene and methylisobutyl ketone (mass ratio, 8:2) is blended with 100 parts by mass of amixture of a radiation curable binder (pentaerythritoltriacrylate(PETA)), dipentaerythritclhexaacrylate (DPHA), and polymethylmethacrylate (PMMA) (mass ratio; PETA/DPHA/PMMA=86/5/9) to prepare acoating composition.

Fine particles are immersed in the resulting coating composition for 24hours. Swollen fine particles are defined as “low cross-linked” fineparticles, and non swollen fine particles are defined as “highcross-linked” fine particles.

The average particle size of the fine particles (B1) is not particularlylimited, and may be similar to that of the organic fine particles (A1).However, in the presence of the radiation curable binder and/or thesolvent, the organic fine particles (A1) are swollen with the radiationcurable binder and/or the solvent, whereby an impregnation layer isformed. Therefore, in the anti-glare film of the present invention,D_(A)1, D_(B)1, D_(A)2, and D_(B)2 preferably satisfy the formula (3):

1.0 μm>D _(A)2−D _(A)1>D _(B)2−D _(B)1≧0  (3)

wherein D_(A)1 represents an average particle size of the organic fineparticles (A1), D_(B)1 represents an average particle size of the fineparticles (B1), D_(A)2 represents an average particle size of theorganic fine particles (A2) in the diffusion layer, and D_(B)2represents an average particle size of the fine particles (B2) in thediffusion layer.

When the formula (3) is satisfied, a surface roughness of the diffusionlayer becomes smooth, and the variation of a refractive index ofparticles contributing to the internal diffusion caused by theimpregnation of the particles with the binder or the like is suppressed,whereby the internal diffusion is easily maintained. Further, thereflection at surfaces of the particles in the diffusion layer isreduced. Therefore, white muddiness and scintillation of the anti-glarefilm of the present invention can be certainly prevented.

In the anti-glare film of the present invention, anti-glare films areprepared using coating compositions including organic fine particleswith different cross-linking degrees, and organic fine particlesachieving a suitable impregnation degree are selected from these as theorganic fine particles (B1).

The amount of the organic fine particles (B1) in the coating compositionis preferably, but is not particularly limited to, 0.5 to 30 parts bymass based on 100 parts by mass of the radiation curable binderdescribed below. If the amount is less than 0.5 parts by mass,scintillation is likely to be generated. If the amount exceeds 30 partsby mass, contrast may be reduced. The lower limit of the amount of theorganic fine particles (B1) is more preferably 1.0 part by mass, and theupper limit of the amount is more preferably 20 parts by mass. If theamount is within the above range, the effect described above maycertainly be achieved.

In the anti-glare film of the present invention, the radiation curablebinder includes a (meth)acrylate monomer as an essential ingredient.

The radiation curable binder preferably swells the organic fineparticles (A1) described above and is preferably transparent. Examplesof the radiation curable binder include an ionizing radiation curingresin which is curable with ultraviolet radiation or electron rays. Theterm “(meth)acrylate” used herein refers to methacrylate and acrylate.

Since the monomer in the present description is curable with ionizingradiation to become a polymer film, the monomer may be any of moleculesthat are to be a structural unit of a basic structure of the polymerfilm, and may include at least one unsaturated bond. That is, if thecured film includes oligomers or prepolymers as a basic unit, themonomer may include oligomers and prepolymers.

In the present invention, the monomer preferably has a molecular weightof 5000 or less.

Examples of the (math) acrylate monomer include compounds having one ortwo or more unsaturated bonds, such as a compound having a (math)acrylate functional group.

Examples of the compound having one unsaturated bond includeethyl(meth)acrylate, ethylhexyl(meth)acrylate, styrene, methylstyrene,and N-vinyl pyrrolidone. Examples of the compound having two or moreunsaturated bonds include reaction products (for example,poly(meth)acrylate esters of polyhydric alcohols) of (meth)acrylate withmultifunctional compounds such as polymethylolpropane tri(meth)acrylate,hexanediol di(meth)acrylate, polypropylene glycol di(meth)acrylate,diethylene glycol di(meth)acrylate, polyethylene glycoldi(meth)acrylate, bisphenol F EO-modified di(meth)acrylate, bisphenol AEO-modified di(meth)acrylate, trimethylolpropane tri(meth)acrylate,dipentaerythritol penta(meth)acrylate, EO-modified isocyanuratedi(meth)acrylate, EO-modified isocyanurate tri(meth)acrylate,PO-modified trimethylolpropane tri(meth)acrylate, EO-modifiedtrimethylolpropane tri(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritolpenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate,1,6-hexanediol di(meth)acrylate, and neopentylglycol di(meth)acrylate.

Examples of the compound having two or more unsaturated bonds furtherinclude urethane(meth)acrylate and polyester(meth)acrylate eachincluding two or more unsaturated bonds.

Examples of the ionizing-radiation curable resin include, in addition tothe (math) acrylate monomer, resins having an unsaturated double bondand a comparatively low molecular weight, such as a polyester resin, apolyether resin, an acrylic resin, an epoxy resin, a urethane resin, analkyd resin, a spiroacetal resin, a polybutadiene resin, and a polythiolpolyene resin.

If the ionizing radiation-curable resin is used as anultraviolet-curable resin, the coating composition preferably includes aphotopolymerization initiator.

Specific examples of the photopolymerization initiator includeacetophenones, benzophenones, Michier-benzoyi benzoate, α-amyloximeesters, thioxanthones, propiophenones, benzyls, benzoins, and acylphosphine oxides. Also, the composition preferably further includes aphotosensitizer, and specific examples thereof include butylamine,triethylamine, and poly-n-butyl phosphine.

In the case that the ultraviolet-curable resin is a resin having aradically polymerizable unsaturated group, one of acetophenones,benzophenones, thioxanthones, benzoin, and benzoin methyl ether, or anycombination of these is preferably used as the photopolymerizationinitiator. In the case that the ultraviolet-curable resin is a resinhaving a cat ionically polymerizable functional group, one of aromaticdiazonium salts, aromatic sulfonium salts, aromatic iodonium salts,metallocene compounds, and benzoin sulfonic esters, or any combinationof these may be used as the photopolymerization initiator.

The amount of the photopolymerization initiator is preferably 0.1 to 10parts by mass based on 100 parts by mass of the ultraviolet-curableresin.

The ionizing radiation-curable resin may be used together with asolvent-drying resin (a resin such as a thermoplastic resin that becomesa coating film only by drying, in the coating process, the solvent addedfor adjusting the solid content). In this case, the solvent-drying resinserves as an additive, and an ionizing radiation-curable resin is mainlyused as it. The amount of the solvent-drying resin is preferably 40% bymass or less based on the total solid contents of the resin componentincluded in the coating composition.

A major example of the solvent-drying resin may be a thermoplasticresin. As the thermoplastic resin, common thermoplastic resins are used.Addition of the solvent drying resin enables to effectively preventgeneration of a coating-film defect on a coated surface.

Specific examples of preferable thermoplastic resins include styreneresins, (meth)acrylic resins, vinyl acetate resins, vinyl ether resins,halogen-containing resins, alicyclic olefin resins, polycarbonateresins, polyester resins, polyamide resins, cellulose derivatives,silicone resins, rubbers, and elastomers.

The thermoplastic resin is usually preferably amorphous and soluble inan organic solvent (particularly a common solvent that can dissolvepolymers and curable compounds). Particularly, the resin preferably hasa high forming property or a high film forming property, hightransparency and high weather resistance. Examples of the resin includestyrene resins, (meth)acrylic resins, alicyclic olefin resins, polyesterresins, and cellulose derivatives (cellulose esters and the like).

In a preferable aspect of the present invention, if a material of thelight-transmitting substrate is a cellulose resin such as triacetylcellulose “TAC”, preferable specific examples of the thermoplastic resininclude cellulose resins such as nitrocellulose, acetyl cellulose,cellulose acetate propionate, and ethyl hydroxyethyl cellulose. Use ofthe cellulose resin can improve the transparency and the adhesionbetween the light-transmitting substrate and the diffusion layer.

The coating composition may further contain a thermosetting resin.Examples of the thermosetting resin include, phenol resins, urea resins,diallyl phthalate resins, melamine resins, guanamine resins, unsaturatedpolyester resins, polyurethane resins, epoxy resins, amino alkyd resins,melamine-area co-condensation resins, silicon resins, and polysiloxaneresins. A curing agent such as a crosslinking agent and a polymerizationinitiator, a polymerization accelerator, a solvent, a viscosityadjustment agent, or the like is used together with the thermosettingresin if necessary.

In the anti-glare film of the present invention, Δ_(A) and Δ_(B)preferably satisfy the formula (1):

|Δ_(A)|<|Δ_(B)|  (1)

wherein Δ_(A) represents a difference between a refractive index of theradiation curable binder and a refractive index of the organic fineparticles (A1) and Δ_(B) represents a difference between a refractiveindex of the radiation curable binder and a refractive index of theorganic fine particles (B1).

When the formula (1) is satisfied, the anti-glare film can be obtainedin which scintillation because of internal diffusion of the organic fineparticles (A) with a small diffusion angle and internal diffusion of theorganic fine particles (B) with a large diffusion angle is not observedand screen intensity is uniform.

The refractive indexes of the radiation curable binder, the organic fineparticles (A1), and the organic fine particles (B1) may be measured byany method such as the Becke method, the minimum deviation angle method,the deflection angle analysis, the mode-line method, and theellipsometry method. Such methods may be used for measuring fineparticles removed from an anti-glare film product in some way, as wellas the material itself.

If the radiation curable binder includes resins and additives inaddition to the (meth)acrylate, the refractive index of the radiationcurable binder is determined as the refractive index derived from allresin and of additive components other than the fine particles.

The refractive index of the radiation curable binder is preferablymeasured by the Becke method using only a binder portion cut from acured film. The difference between the refractive index of the organicfine particles and the refractive index of the resin component may bedetermined by measuring the phase difference using a transmissionphase-shifting laser microscope interferometer PLM-OPT manufactured byNTT Advanced Technology Corp. Therefore, the refractive index of theorganic fine particles may be determined as the refractive index of theresin component±the refractive-index difference.

Examples of the solvent include, but are not particularly limited to,alcohols (for example, methanol, ethanol, isopropanol, butanol, andbenzyl alcohol); ketones (for example, acetone, methyl ethyl ketone,methyl isobutyl ketone, cyclohexanone, and cyclopentanone); esters (forexample, methyl acetate, ethyl acetate, propyl acetate, butyl acetate,methyl formate, ethyl formate, propyl formate, and butyl formate);aliphatic hydrocarbons (for example, hexane and cyclohexane);halogenated hydrocarbons (for example, methylene chloride, chloroform,and carbon tetrachloride); aromatic hydrocarbons (for example, benzene,toluene, and xylene); amides (for example, dimethylformamide,dimethylacetamide, and n-methyl pyrolidone); ethers (for example,diethyl ether, dioxane, and tetrahydrofuran); and ether alcohols (forexample, 1-methoxy-2-propanol).

Both the radiation curable binder and the solvent may be ones capable ofswelling the organic fine particles (A1) or one of them may be onecapable of swelling the organic fine particles (A1).

The impregnation layer of the organic fine particles (A1) can becertainly formed in the presence of the solvent capable of swelling theorganic fine particles (A1) without being dependent on the degree ofswelling by the radiation curable binder. Therefore, at least thesolvent is preferably one capable of swelling the organic fine particles(A1). It is considered that this is because the solvent firstly acts onthe organic fine particles (A1) and swells the particles (A1), and thenlow molecular weight components included in the radiation curable binderpenetrate into the particles.

In the anti-glare film of the present invention, the combination of a(meth)acrylate monomer as the radiation curable binder and ketones oresters as the solvent is preferably used as the combination of theradiation curable binder and the solvent. This is because a(meth)acrylate monomer with a small molecular weight easily penetratesinto the particles (A1) and ketones and esters well swell the organicfine particles (A1).

The swelling degree of the organic fine particles (A1) is adjusted bymixing the solvent, whereby the penetration amount of the low molecularweight component of the radiation curable binder can be controlled.

When cellulose triacetate (hereinafter, also referred to as a TACsubstrate) is used as the light-transmitting substrate, a solventcapable of swelling the TAC substrate to prevent adhesion at theinterface between the light transmitting substrate and the diffusionlayer or prevent generation of interference fringe at the interface; ora solvent capable of allowing the solvent and the low molecular weightcomponent in the resin components penetrate into the TAC substrate ispreferably used. A common solvent is preferably used for the solventswelling the organic fine particles (A) and the solvent penetrating intothe TAC substrate. That is, if the solvent penetrating into the TACsubstrate is similar to the solvent used for preparing an impregnationlayer in the organic fine particles (A), compounds included in thecoating composition are remarkably well balanced and the coatingcomposition can be excellently stably processed into the anti-glare filmeven if the process takes a long time.

Methyl isobutyl ketone and the like are preferred as such a solvent.Preferred examples of the low molecular weight component in the resincomponent include pentaerythritol tri(meth)acrylate, pentaerythritolpenta(meth)acrylate, dipentaerythritol penta(meth)acrylate, anddipentaerythritol hexa(meth)acrylate.

The coating composition preferably further includes a lamellar inorganiccompound. The diffusion layer including the lamellar inorganic compoundcan improve shock resistance such as prevention of curl, ultravioletlight resistance, and crack resistance.

Examples of the lamellar inorganic compound include, but are notparticularly limited to, montmorillonite, beidellite, nontronite,saponite, hectorite, sauconite, stevensite, vermiculite, halloysite,kaolinite, endellite, dickite, talc, pyrophyllite, mica, margarita,muscovite, phlogopite, tetrasilylic mica, taeniolite, antigorite,chlorite, cookeite, and nimite. These lamellar inorganic compounds maybe natural products or synthesized products.

Among the lamellar inorganic compounds, an inorganic compound includingan element. Si, Al, Mg, or O is preferred. Talc is preferred as thecompound including such an element. For example, when talc is used asthe lamellar inorganic compound, cross-linked acrylic beads are used asthe organic fine particles (A1), and styrene is used as the organic fineparticles (B1), the aggregation degrees of the organic fine particles(A2) and the organic fine particles (B2) in the diffusion layer can bepreferably controlled. This achieves an anti-glare property, preventionof white muddiness, and prevention of scintillation of the anti-glarefilm, at a high level.

It is considered that this is because the talc is highly lipophilic.That is, it is considered that the talc with high lipophilicity controlsthe aggregation of the organic fine particles (A1) (cross-linked acrylicresin) with a hydrophilic property and the organic fine particles (B1)(styrene) with a lipophilic property.

The lamellar inorganic compound refers to an inorganic compound with alamellar structure, and includes an inorganic compound with a needlelikeappearance or a fibrous appearance when the cross section is observedunder a microscope.

The amount of the lamellar inorganic compound in the coating compositionis preferably 0.5 to 40 parts by mass based on 100 parts by mass of theradiation curable binder. If the amount is less than 0.5 parts by mass,the shock resistance of the anti-glare film of the present inventionand/or the dispensability of the organic fine particles (A2) and thelike of the anti-glare film of the present invention may becomeinsufficient. If the amount exceeds 40 parts by mass, the coatingcomposition forming the diffusion layer may be toe viscous to be coatedor the surface roughness of the resulting coating may not be controlled.The lower limit of the amount of the lamellar inorganic compound is morepreferably two parts by mass, and the upper limit of the amount is morepreferably 20 parts by mass. If the amount is within the above range,the effects of the shock resistance and/or the dispersibility of thefine particles may be further exerted and the surface roughness iseasily controlled.

The coating composition may be prepared by mixing the materialsdescribed above.

The method of preparing the coating composition by mixing the materialsis not particularly limited. For example, a paint shaker or a bead millmay be used.

The diffusion layer may be formed by applying the coating composition onat least one surface of the light-transmitting substrate, drying thecoating composition to form a coating, and curing the coating.

The method of applying the coating composition is not particularlylimited, and examples thereof include roll coating, Meyer bar coating,gravure coating, and die coating.

The thickness of the coating resulting from the coating composition isnot particularly limited, and determined depending on, for example, theshape of the surface roughness of the coating and the materials to beused. If the thickness is 1 μm or more, the coating is excellent in ahard coat property. If the thickness is 20 μm or less, curl is lesslikely to be generated. Therefore, the thickness is preferably about 1μm to about 20 μm, more preferably 2 to 15 μm, and still more preferably2 μm to 10 μm.

The thickness of the diffusion layer may be determined by thecross-sectional SEM observation. Such a thickness is determined by thefollowing way. The distance between the surface of the diffusion layerincluding no organic fine particles (A2) and the interface of the lighttransmitting substrate is measured at 5 or more different points. Theaverage of the resulting values is calculated as the thickness of thediffusion layer.

As described above, the organic fine particles (A2) are prepared byswelling the organic fine particles (A1) with the radiation curablebinder and/or the solvent and forming an impregnation layer impregnationwith the radiation curable binder. The organic fine particles (A2) maybe prepared in the coating composition or in the coating formed on thelight-transmitting substrate.

The prepared coating composition is preferably allowed to stand for acertain period of time before the diffusion layer is formed.

If the diffusion layer is formed without allowing the coatingcomposition to stand, a sufficient impregnation layer may not be formedin the organic fine particles (A2) in the diffusion layer even if thecross-linking degree of the organic fine particles (A) to be used andthe swelling degree of the organic fine particles (A) swollen with theradiation curable binder and/or the solvent are suitably adjusted.

The coating composition may be allowed to stand for a certain period oftime that depends on the type, cross-linking degree, and particle sizeof the organic fine particles (A) to be used, and the type of theradiation curable binder and/or the solvent to be used. For example, thecoating composition is preferably allowed to stand for about 12 hours toabout 48 hours.

The coating formed on the light-transmitting substrate may be dried ifnecessary, and cured to form the diffusion layer.

The method of curing the coating is not particularly limited, and thecoating is preferably cured by UV irradiation. The ultraviolet rays in awavelength band from 190 to 380 nm are preferably used for the curing.The curing by the ultraviolet rays may be performed using, for example,a metal halide lamp, a high-pressure mercury lamp, a low-pressuremercury lamp, an ultra-high-pressure mercury lamp, a carbon arc, or ablack light fluorescent lamp. Specific examples of a source of suchelectron rays include electron beam accelerators of Cockcroft-Waltontype, van de Graaff type, resonance transformer type, insulating coretransformer type, linear type, dynamitron type, and high frequency type.

In the anti-glare film of the present invention, the diffusion layer hasa surface roughness.

The diffusion layer preferably includes projections (hereinafter, alsoreferred to as projections (A)) at positions corresponding to theorganic fine particles (A) in the diffusion layer. The height of theprojections (A) is preferably lower than that of projections(hereinafter, also referred to as projections (C)) at positionscorresponding to organic fine particles (C) in the surface of adiffusion layer (C) that satisfies all the following requirements (1),(2), and (3):

Requirement (1): the diffusion layer (C) is formed in the sameconditions as the diffusion layer containing the organic fine particles(A), except that the organic fine particles (C) are used instead of theorganic fine particles (A);

Requirement (2): the average particle size of the organic fine particles(C) in the diffusion layer (C) is the same as that of the organic fineparticles (A) in the diffusion layer; and

Requirement (3): no impregnation layer is formed in each of the organicfine particles (C) in the diffusion layer (C).

The projections (A) have a height lower than that of the projections(C), and are gently curved. The anti-glare film of the present inventionincluding a diffusion layer with such projections is excellent in ananti-glare property, prevention of white muddiness, and prevention ofscintillation.

It is considered that this is because the organic fine particles (A) inthe coating to be cured are the organic fine particles (A2) eachincluding the impregnation layer, and the organic fine particles (A2)are very much more flexible than the organic fine particles (C). Thatis, although the radiation curable binder shrinks when the coating iscured, cure shrinkage of the surface where the organic fine particles(A2) are placed is more reduced than that of the surface where noorganic fine particles (A) are placed because of the small amount of theradiation curable binder. However, since the organic fine particles (A2)are excellent in flexibility, the organic fine particles (A) deform dueto the cure shrinkage of the coating. As a result, the height of theformed projections (A) may be lower than that of the projections (C)formed in the surface of the diffusion layer (C) that includesinflexible organic fine particles (C). Therefore, the projections (A)become smooth.

The height of the projections refers to a height n (n is 1 to 10) whichis a distance from the top of a projection to the bottom of a depressionbetween two adjacent projections in the surface, and is measured byobserving the surface of the anti-glare film with AFM. The height n ismeasured at 10 points, and the average value was adopted for the heightof the projections.

Since the anti-glare film of the present invention has the diffusionlayer described above, the adhesion between the organic fine particles(A) in the diffusion layer and the cured product of the radiationcurable binder is extremely excellent. The anti-glare film of thepresent invention is subjected to a mandrel test. The results are thatthe film is not cracked preferably when a mandrel of 10 mm diameter isused, more preferably when a mandrel of 8 mm diameter is used, and stillmore preferably when a mandrel of 6 mm diameter is used.

Since the impregnation layer is formed in each of the organic fineparticles (A) in the diffusion layer and the radiation curable binder ismixed in the impregnation layer, the difference between the refractiveindex of the organic fine particles (A) (impregnation layer) in thediffusion layer and the refractive index of the cured product of theradiation curable binder is reduced. Therefore, reflection at theinterface can be preferably reduced. In addition, the impregnation layerhas an appropriate thickness and the center portion of each of theorganic fine particles (A) retains the same refractive index as that ofthe original organic fine particles (A). Therefore, appropriate internaldiffusion can be exerted and scintillation can be preferably prevented.

Further, the projections formed at positions corresponding to theorganic fine particles (A) in the diffusion layer are small in heightand gently curved.

This achieves an anti-glare property, prevention of white muddiness, andprevention of scintillation, of the anti-glare film, at a high level.

The anti-glare film of the present invention preferably has a hazevariation during a 60° C., 90% RH, 1000-hour moisture and heatresistance test of 1.5% or less. If the haze variation exceeds 1.5%, theanti-glare film may have low moisture and heat resistance and theanti-glare performance may change over time in response to temperatureand moisture changes. The haze variation is preferably 1.0% or less.Such moisture and heat resistance can be achieved in the anti-glare filmhaving the diffusion layer including the organic fine particles (A) withthe impregnation layer.

Here, the haze is determined using a haze meter HM150 (product name,manufactured by Murakami Color Research Laboratory Co., Ltd.) accordingto the haze defined by JIS K 7136. The haze values in the presentinvention are all measured by the method.

A method for producing such an anti-glare film of the present inventionis also one aspect of the present invention.

That is, a method for producing an anti-glare film of the presentinvention includes a light-transmitting substrate and a diffusion layerhaving a surface roughness and provided on at least one surface of thelight transmitting substrate. The method comprises forming the diffusionlayer by applying, on the at least one surface of the light-transmittingsubstrate, a coating composition including organic fine particles (A), aradiation curable binder that includes a (meth)acrylate monomer as anessential component, and a solvent; drying the coating composition toform a coating; and curing the coating, the radiation curable binderand/or the solvent including a component that swells the organic fineparticles (A), the organic fine particles (A) each having animpregnation layer that is impregnated with the radiation curable binderand has an average thickness of 0.01 to 1.0 μm.

In the method for producing the anti-glare film of the presentinvention, a material and the like constituting the coating compositionare the same as those of the above-described anti-glare film of thepresent invention.

Further, the process for forming the diffusion layer is the same as thatfor forming the above-described anti-glare film of the present inventionis used.

A polarizer provided with a polarizing element, comprising theanti-glare film of the present invention is also one aspect of thepresent invention. A light-transmitting substrate is attached to thesurface of the polarizing element.

Examples of the polarizing element include, but are not particularlylimited to, films dyed with iodine or the like and stretched, such as apolyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetalfilm, and an ethylene-vinyl acetate copolymer saponified film. In thelamination of the polarizing element and the anti-glare film of thepresent invention, the light-transmitting substrate is preferablysubjected to saponification treatment. The saponification treatmentmakes the adhesion good, and an antistatic effect can also be achieved.

The present invention also relates to an image display device includingthe anti-glare film or the polarizer on the outermost surface. Examplesof the image display device include LCDs, PDPs, FEDs, ELDs (organic EL,inorganic EL), CRTs, touch panels, and electronic paper.

The LCDs include a light-transmitting display and a light sourceapparatus for irradiating the light-transmitting display from thebackside. When the image display device of the present invention isLCDs, the anti-glare film of the present invention or the polarizer ofthe present invention is formed on the surface of the light-transmittingdisplay.

When the present invention directs to a liquid crystal display devicehaving the anti-glare film, a light source of the light source apparatusemits light to the anti-glare film from the underside. Here, in an STNliquid crystal display device, a retardation plate may be disposedbetween a liquid crystal display element and a polarizer. An adhesivelayer may be provided between layers of the liquid crystal displaydevice as required.

The PDPs include a surface glass substrate and a back glass substratefacing to the surface glass substrate. Discharge gas is enclosed betweenthe substrates. When the image display device of the present inventionis PDP, the image display device includes the anti-glare film describedabove on the surface of the surface glass substrate or a front plate(glass substrate or film substrate) thereof.

The image display device described may be an ELD device in whichluminous substances such as zinc sulfide and diamines which emit lightthrough the application of a voltage are deposited on a glass substrateby vapor deposition and display is performed by controlling a voltageapplied to the substrate, or a CRT display device that converts electricsignals to light to generate visible images. In this case, the imagedisplay device includes the anti-glare film on the outermost surface ofeach of the display devices or on the surface of a front plate thereof.

The anti-glare film of the present invention may be used for displays oftelevisions and computers. Particularly, it may be suitably used at thesurfaces of high definition displays such as PDPs, ELDs, touch panels,and electronic paper.

Advantageous Effects of Invention

In the anti-glare film of the present invention, projections atpositions corresponding to organic fine particles (A) in the surface ofthe diffusion layer are small in height and gently curved. Therefore, ifthe anti-glare film is used in a high definition display, an excellentanti-glare property, excellent prevention of white muddiness, andexcellent prevention of scintillation can be achieved.

The impregnation layer described above is formed in the organic fineparticles (A) in the diffusion layer. Since the radiation curable binderis mixed in the impregnation layer, the reflection at the interfacebetween the organic fine particles (A) (impregnation layer) in thediffusion layer and the cured product of the radiation curable bindercan be preferably reduced.

Further, the adhesion between the organic fine particles (A) in thediffusion layer and the cured product of the radiation curable binder isextremely excellent. Therefore, if the anti-glare film of the presentinvention is used in a sheet-like liquid crystal display, no cracks aregenerated at the interface between the organic fine particles (A) andthe cured product of the radiation curable binder.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional SEM image of a diffusion layer of ananti-glare film in accordance with Example 1.

FIG. 2 is a cross-sectional. SEM image of a diffusion layer of ananti-glare film in accordance with Example 2.

DESCRIPTION OF EMBODIMENTS

The present invention will be described by means of the followingExamples which, however, are not intended to limit the scope of thepresent invention.

Example 1

First, triacetylcellulose (80 μm thickness, manufactured by FujiFilmCorp.) was prepared as a light transmitting substrate.

Next, a coating composition was prepared by mixing the followingingredients: a mixture of pentaerythritol triacrylate (PETA),dipentaerythritol hexaacrylate (DPHA), and polymethyl methacrylate(PMMA) (mass ratio: PETA/DPHA/PMMA=86/5/9) (refractive index aftercuring: 1.51) as a radiation curable binder;1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by BASF)as a photopolymerization initiator in an amount of 3 parts by mass basedon 100 parts by mass of the binder solid content; acrylic particles(refractive index: 1.49, average particle size: 5.0 μm) as organic fineparticles (A) in an amount of 9.0 parts by mass based on 100 parts bymass of the radiation curable binder; and a mixture of toluene andisopropyl alcohol (mass ratio: 7:3) as a solvent in an amount of 190parts by mass based on 100 parts by mass of the radiation curablebinder.

The resulting coating composition was allowed to stand for 24 hours,applied on the light-transmitting substrate using a meyer bar, and driedfor 1 minute with dry air at 70° C. at a flow rate of 1.2 m/s.

The resulting coating was irradiated with ultraviolet rays (200 mJ/cm²under a nitrogen atmosphere) to cure the radiation curable binder,whereby a diffusion layer was formed. Thus, an anti-glare film wasprepared. The thickness of the diffusion layer was 6.0 μm.

Examples 2 to 8

Anti-glare films were prepared in the same manner as Example 1, exceptthat the ingredients of the coating composition and the time forallowing the coating composition to stand were set in accordance withTable 1.

Comparative Example 1

First, triacetylcellulose (80 μm thickness, manufactured by FujiFilmCorp.) was prepared as a light-transmitting substrate.

Next, a coating composition was prepared by mixing the followingingredients: a mixture (refractive index: 1.47) of a vinyl acetate resin(refractive index: 1.46) and a methyl methacrylate resin (refractiveindex: 1.49) (mass ratio; vinyl acetate resin/methyl methacrylateresin=60/40) as a binder; acrylic particles (refractive index: 1.49,average particle size: 5.0 μm) as organic fine particles (A) in anamount of 9.0 parts by mass based on 100 parts by mass of the binder;and a mixture of toluene and methyl ethyl ketone (mass ratio: 7:3) as asolvent in an amount of 190 parts by mass based on 100 parts by mass ofthe binder.

The resulting coating composition was allowed to stand for 24 hours,applied onto the light-transmitting substrate using a meyer bar, anddried for 1 minute with dry air at 70′C at a flow rate of 1.2 m/s. Thethickness of the resulting coating was 6.0 μm.

Since both the vinyl acetate resin and the methyl methacrylate resinwere non-reactive copolymers, the refractive index does not vary duringthe curing.

Comparative Examples 2 to 5

Anti-glare films were prepared in the same manner as Example 1, exceptthat the ingredients of the coating composition and the time forallowing the coating composition to stand were set in accordance withTable 1.

TABLE 1 Organic fine Fine Lamellar inorganic Time for allowing particle(A) particle (B) compound Type of coating composition Binder Type AmountΔ_(A) Type Amount Δ_(B) Type Amount solvent to stand (hour) Example 1 QA 9.0 0.02 — — — — — Z 24 Example 2 P A 9.0 0.02 — — — M 2.0 Y 24Example 3 P A 6.0 0.02 D 5.0 0.09 M 2.0 Y 24 Example 4 P A 6.0 0.02 E5.0 0.09 M 2.0 Y 24 Example 5 P C 6.0 0.02 E 5.0 0.09 M 2.0 Y 24 Example6 P A 9.0 0.02 — — — — — Y 24 Example 7 Q A 6.0 0.02 F 5.0 0.01 M 2.0 Y24 Example 8 Q A 9.0 0.02 — — — — — Y 48 Comparative R A 9.0 0.02 — — —— — X 24 Example 1 Comparative R A 6.0 0.02 D 5.0 0.13 M 2.0 X 24Example 2 Comparative P B 9.0 0.02 — — — — — Y 24 Example 3 ComparativeQ B 9.0 0.02 D 5.0 0.09 M 2.0 Y 24 Example 4 Comparative Q A 9.0 0.02 —— — — — Y 60 Example 5

In Table 1, symbols showing the types of the organic fine particles (A),the fine particles (B), the radiation curable binder, and the solventare described in detail below. Amounts (parts by mass) of the organicfine particles (A), the fine particles (B), and the lamellar inorganiccompound are based on 100 parts by mass of the radiation curable binder.

Organic Fine Particle A

A: Low cross-linked acrylic particle (refractive index: 1.49, averageparticle size: 5.0 lμm, manufactured by Soken Chemical & EngineeringCo., Ltd.)

B: High cross-linked acrylic particle (refractive index: 1.49, averageparticle size: 5.0 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.)

C: Low cross-linked acrylic particle (refractive index: 1.49, averageparticle size: 3.5 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.)

Particle B

D: High cross-linked polystyrene particle (refractive index: 1.59,average particle size: 3.3 μm, manufactured by Soken Chemical &Engineering Co., Ltd.)

E: Low cross-linked polystyrene particle (refractive index: 1.59,average particle size: 5.0 μm, manufactured by Soken Chemical &Engineering Co., Ltd.)

F: High cross-linked acrylic-styrene particle (refractive index: 1.52,average particle size: 3.0 μm, manufactured by Soken Chemical &Engineering Co., Ltd.)

Lamellar Inorganic Compound

M: Talc (refractive index: 1.57, average particle size: 0.8 μm,manufactured by Nippon Talc Co., Ltd.)

Radiation Curable Binder

P: A mixture of pentaerythritol triacrylate (PETA), dipentaerythritolhexaacrylate (DPHA), and polymethyl methacrylate (PMMA) (Mass ratio:PETA/DPHA/PMMA=86/5/9) (refractive index after curing: 1.51)

Q: Pentaerythritol triacrylate (PETA) (refractive index after curing:1.51)

R: A mixture of 60 parts by mass of a vinyl acetate resin and 40 partsby mass of a methyl methacrylate resin (refractive index 1.47)(refractive index does not vary during the curing because the mixture isa copolymer)

Solvent

X: A mixture of toluene and methyl ethyl ketone (mass ratio: 7:3)

Y: A mixture of toluene and methyl isobutyl ketone (mass ratio: 8:2)

Z: A mixture of toluene and isopropyl alcohol (mass ratio: 7:3)

The anti-glare films obtained in Examples and Comparative Examples wereevaluated for the following criteria. Table 2 shows the results.

Thickness of Impregnation Layer

The anti-glare films obtained in Examples and Comparative Examples weresubjected to the following measurement. Each anti-glare film was cut inthe thickness direction of a diffusion layer, the cross section thereofincluding at least one organic fine particle (A) was observed at 3000×to 50000× magnification using SEM, the thickness of a layer of theorganic fine particle into which the radiation curable binder penetrateswas measured at two points for each of five organic fine particles, andthe average of the resulting 10 measurement values was calculated. Thetwo points selected for the measurement were such that the interfacebetween the particle (A) and the binder around the particle wasrelatively clearly observed and the amount of the radiation curablebinder penetrating into the organic fine particle was the largest. FIG.1 shows a cross-sectional SEM image of the diffusion layer of theanti-glare film in accordance with Example 1 FIG. 2 shows across-sectional SEM image of the diffusion layer of the anti-glare filmin accordance with Example 2.

Even if the diffusion layer includes particles such as fine particles(B), the thickness of the impregnation layer of the particles can bemeasured by the same method for measurement of the organic fineparticles (A).

Haze

The haze values of the anti-glare films obtained in Examples andComparative Examples were determined using a haze meter HM-150(manufactured by Murakami Color Research Laboratory Co., Ltd.) inaccordance with the haze defined by JIS K 7136 (2000).

A haze variation during a 60° C., 90% RH, 1000-hour moisture and heatresistance test was determined for the anti-glare films obtained inExamples and Comparative Examples.

Mandrel Test

A mandrel test was performed for the anti-glare films obtained inExamples and Comparative Examples using a mandrel of φ6 mm, a mandrel of8 mm diameter, and a mandrel of φ10 mm in accordance with JIS K5600-5-1(1999). The films were evaluated according to the following criteria.

Excellent: no crack is generated in use of φ6 mm mandrelGood: no crack is generated in use of φ8 mm mandrelFair: no crack is generated in use of φ10 mm mandrelPoor: crack is generated in use of φ10 mm mandrel

Contrast

The anti-glare films obtained in Examples and Comparative Examples wereeach pasted on a black acrylic board using a transparent adhesion filmfor an optical film. The states of the anti-glare films are visuallyobserved by 15 subjects from different angles and sensory evaluation wasperformed in a room with an illuminance of 1,000 Lx. Regeneration ofblack gloss was observed and evaluated according to the followingcriteria.

Excellent: Evaluation of “satisfactory” by at least 10 individuals.Good: Evaluation of “satisfactory” by 6 to 9 individuals.Fair: Evaluation of “satisfactory” by 5 to 7 individuals.Poor: Evaluation of “satisfactory” by 4 or fewer individuals.

Scintillation

A polarizer on the outermost surface of a liquid crystal television“KDL-40X2500” produced by Sony Corporation was removed, and a polarizerwith no surface coating was attached instead.

Then, the anti-glare films obtained in Examples and Comparative Exampleswere each attached over the polarizer so that the diffusion layer wasthe outermost surface. The file was attached using a transparentpressure-sensitive adhesive film for an optical film (product with totallight transmittance of 91% or higher, haze of 0.3% or lower, and filmthickness of 20 to 50 μm, for example, one of the MHM Series by NichieiKakoh Co., Ltd.).

The liquid crystal television was installed in a room with anilluminance of about 1,000 Lx, and a white screen was displayed thereon.The white screen was visually observed by 15 subjects at sites about 0.3to 1.0 in distant from the liquid crystal television from differentangles, for example, from right and left and from above and below. Thus,sensory evaluation was performed to evaluate scintillation of the whitescreen display in accordance with the following criteria.

Excellent: Evaluation of “satisfactory” by at least 10 individuals.Good: Evaluation of “satisfactory” by 8 to 9 individuals.Fair: Evaluation of “satisfactory” by 5 to 7 individuals.Poor: Evaluation of “satisfactory” by 4 or fewer individuals.

Hard Coat Property

A pencil hardness test was conducted in accordance with JIS K5600-5-4(1999) by drawing five lines with a 3H pencil under a load of 750 g onthe surface of each anti-glare film obtained in Examples, ComparativeExamples, and Reference Examples.

Excellent: no scratch was observed in 3H pencil hardness testGood: 1 to 2 scratches were observed in 3H pencil hardness test.Fair: 3 to 4 scratches were observed in 3H pencil hardness testPoor: 5 scratches were observed in 3H pencil hardness test

TABLE 2 Organic fine particle Impregnation layer Haze variation during(A) Impregnation layer D_(A)2- thickness (μm) of moisture and heatMandrel Scintil- Hard coat thickness (μm) D_(A)1 fine particle (B) Hzresistance test test Contrast lation property Example 1 0.05 0.07 — 11.10.8 Fair Good Fair Good Example 2 0.3 0.42 — 9.7 0.2 Good Excellent GoodExcellent Example 3 0.3 0.42 0 17.4 0.9 Good Good Excellent Good Example4 0.3 0.42 0.1 14.8 0.1 Excellent Excellent Excellent Excellent Example5 0.2 0.28 0.1 15.8 0.6 Excellent Fair Good Excellent Example 6 0.3 0.42— 10.5 0.3 Good Good Fair Good Example 7 0.6 0.84 0 8.1 0.7 Good FairFair Good Example 8 0.8 0.95 — 8.3 0.2 Excellent Good Fair GoodComparative 0 0.00 — 13.4 6.4 Poor Fair Fair Poor Example 1 Comparative0 0.00 0 19.3 4.1 Poor Fair Excellent Poor Example 2 Comparative 0 0.00— 11.8 3.5 Poor Fair Fair Fair Example 3 Comparative 0 0.00 0 16.7 5.6Poor Good Good Fair Example 4 Comparative 1.3 1.41 — 8.3 0.2 ExcellentExcellent Poor Good Example 5

As shown in Table 2, in the anti-glare films in accordance withExamples, the organic fine particles (A) in the diffusion layer have aradiation curable binder-containing impregnation layer with an averagethickness of 0.05 to 0.8 μm. It was confirmed that the radiation curablebinder is mixed in the impregnation layer. The haze variation of theanti-glare films according to Examples during a moisture and heatresistance test was 0.9% or less. The evaluation results of the mandreltest and scintillation of the film in Example 1, the evaluation resultsof the contrast of the films in Examples 5 and 7, and the evaluationresults of the scintillation of the films in Examples 1, and 6 to 8 were“fair”. However, the overall evaluation results of the mandrel test,contrast, and scintillation were favorable.

An impregnation layer was not formed in the organic fine particles (A)in the diffusion layer of the anti-glare films in accordance withComparative Examples 1 to 4. Therefore, all the evaluation results ofthe haze variation during a moisture and heat resistance test, themandrel test, the contrast, and the scintillation were not so good. Theimpregnation layer with a thickness of 1.3 μm was formed in the organicfine particles (A) in the diffusion layer of the anti-glare film inaccordance with Comparative Example 5. However, the anti-glare film waspoor in scintillation.

INDUSTRIAL APPLICABILITY

The anti-glare film of the present invention can be preferably used incathode ray tubes (CRTs), liquid crystal displays (LCDs), plasmadisplays (PDPs), electroluminescence displays (ELDs), and displays oftouch panels and electronic paper, and particularly used in highdefinition displays.

1. An anti-glare film, comprising: a light-transmitting substrate; and adiffusion layer having a surface roughness and provided on at least onesurface of the light-transmitting substrate, wherein the diffusion layeris obtainable by applying, on the at least one surface of thelight-transmitting substrate, a coating composition including organicfine particles (A) and a radiation curable binder that includes a(meth)acrylate monomer as an essential component, drying the coatingcomposition to form a coating, and curing the coating, the organic fineparticles (A) in the diffusion layer each have an impregnation layerthat is impregnated with the radiation curable binder, and theimpregnation layer has an average thickness of 0.05 to 1.0 μm.
 2. Theanti-glare film according to claim 1, wherein a haze variation during a60° C., 90% RH, 1000-hour moisture and heat resistance test is 1.5% orless.
 3. The anti-glare film according to claim 1, wherein the diffusionlayer further includes fine particles (B) with an average particle sizeof smaller than the average particle size of the organic fine particles(A).
 4. The anti-glare film according to claim 1, wherein the coatingcomposition includes at least a solvent that swells the organic fineparticles (A).
 5. The anti-glare film according to claim 3, whereinΔ_(A) and Δ_(B) satisfy the formula (1):|Δ_(A)|<|Δ_(B)|  (1) wherein Δ_(A) represents a difference between arefractive index of the radiation curable binder and a refractive indexof the organic fine particles (A) and Δ_(B) represents a differencebetween a refractive index of the radiation curable binder and arefractive index of the fine particles (B).
 6. The anti-glare filmaccording to claim 3, wherein D_(A)1 and D_(A)2 satisfy the formula (2):0.01 μm<D _(A)2−D _(A)1<1.0 μm  (2) wherein D_(A)1 represents an averageparticle size of the organic fine particles (A) and D_(A)2 represents anaverage particle size of the organic fine particles (A) in the diffusionlayer.
 7. The anti-glare film according to claim 3, wherein D_(A)1,D_(B)1, D_(A)2, and D_(B)2 satisfy the formula (3):1.0 μm>D _(A)2−D _(A)1>D _(B)2−D _(B)1≦0  (3) wherein D_(A)1 representsan average particle size of the organic fine particles (A), D_(B)1represents an average particle size of the fine particles (B), D_(A)2represents an average particle size of the organic fine particles (A) inthe diffusion layer, and D_(B)2 represents an average particle size ofthe fine particles (B) in the diffusion layer.
 8. The anti-glare filmaccording to claim 3, wherein the fine particles (B) are organic fineparticles.
 9. The anti-glare film according to claim 1, wherein thediffusion layer further includes a lamellar inorganic compound.
 10. Theanti-glare film according to claim 9, wherein the lamellar inorganiccompound is talc.
 11. The anti-glare film according to claim 1, whereinthe diffusion layer has projections at positions corresponding to theorganic fine particles (A) in the surface of the diffusion layer, theprojections having a height lower than the height of projections atpositions corresponding to organic fine particles (C) in the surface ofa diffusion layer (C), wherein the diffusion layer (C) satisfy all thefollowing requirements (1), (2), and (3): Requirement (1): the diffusionlayer (C) is formed in the same conditions as the diffusion layercontaining the organic fine particles (A), except that the organic fineparticles (C) are used instead of the organic fine particles (A);Requirement (2): the average particle size of the organic fine particles(C) in the diffusion layer (C) is the same as the average particle sizeof the organic fine particles (A) in the diffusion layer; andRequirement (3): no impregnation layer is formed in each of the organicfine particles (C) in the diffusion layer (C).
 12. A method forproducing an anti-glare film that includes a light-transmittingsubstrate and a diffusion layer having a surface roughness and providedon least one surface of the light-transmitting substrate, the methodcomprising forming the diffusion layer by applying, on the at least onesurface of the light-transmitting substrate, a coating compositionincluding organic fine particles (A), a radiation curable binder thatincludes a (meth)acrylate monomer as an essential component, and asolvent; drying the coating composition to form a coating; and curingthe coating, the radiation curable binder and/or the solvent including acomponent that swells the organic fine particles (A), the organic fineparticles (A) each having an impregnation layer that is impregnated withthe radiation curable binder and has an average thickness of 0.05 to 1.0μm, anti-glare films are prepared using coating compositions includingorganic fine particles with different cross-linking degrees, and organicfine particles achieving a suitable impregnation degree are selectedfrom these as the organic particle (A).
 13. A polarizer provided with apolarizing element, the polarizer comprising the anti-glare filmaccording to claim 1, provided on a surface of the polarizing element.14. An image display device, comprising the anti-glare film according toclaim 1, or a polarizer comprising said anti-glare film on the outermostsurface of the image display device.
 15. The anti-glare film accordingto claim 2, wherein the diffusion layer further includes fine particles(B) with an average particle size of smaller than the average particlesize of the organic fine particles (A).
 16. The anti-glare filmaccording to claim 2 wherein the coating composition includes at least asolvent that swells the organic fine particles (A).
 17. The anti-glarefilm according to claim 3 wherein the coating composition includes atleast a solvent that swells the organic fine particles (A).
 18. Theanti-glare film according to claim 4, wherein Δ_(A) and Δ_(B) satisfythe formula (1):|Δ_(A)|<|Δ_(B)|  (1) wherein Δ_(A) represents a difference between arefractive index of the radiation curable binder and a refractive indexof the organic fine particles (A) and Δ_(B) represents a differencebetween a refractive index of the radiation curable binder and arefractive index of the fine particles (B).
 19. The anti-glare filmaccording to claim 4, wherein D_(A)1 and D_(A)2 satisfy the formula (2):0.01 μm<D _(A)2−D _(A)1<1.0 μm  (2) wherein D_(A)1 represents an averageparticle size of the organic fine particles (A) and D_(A)2 represents anaverage particle size of the organic fine particles (A) in the diffusionlayer.
 20. The anti-glare film according to claim 5, wherein D_(A)1 andD_(A)2 satisfy the formula (2):0.01 μm<D _(A)2−D _(A)1<1.0 μm  (2) wherein D_(A)1 represents an averageparticle size of the organic fine particles (A) and D_(A)2 represents anaverage particle size of the organic fine particles (A) in the diffusionlayer.